Working cylinder

ABSTRACT

A drive cylinder comprising a cylinder barrel ( 3 ) extending between two cylinder heads ( 2   a  and  2   b ) and a plurality of ties ( 13 ) distributed about the outer periphery of the cylinder barrel ( 3 ) and bracing the cylinder heads ( 2   a  and  2   b ). Of these of ties at least one is constituted by a profile part ( 26 ) which extends in the peripheral direction ( 14 ) of the cylinder barrel ( 13 ) some distance along its outer periphery and whose profile provides means for the implementation of at least one additional function.

This application is the National Stage of PCT Application No.PCT/EP02/06622 filed on Jun. 15, 2002 which claims priority to GermanApplication No. 20110965.4 filed on Jul. 3, 2001.

FIELD OF THE INVENTION

The invention relates to a drive cylinder as is more especially employedin pneumatics or hydraulics.

BACKGROUND OF THE INVENTION

State of the art drive cylinders may comprise a cylinder barrelextending between two cylinder heads and designed in the form of aprofile tube which owing to its profile renders possible certainadditional functions, as for example the attachment of sensors inmounting grooves or the passage of actuating fluid through integratedducts. In the special case of a design in the form of an aluminumextruded profile an extremely economic integration of numerousadditional functions is possible.

Presently there is however the problem that cylinder barrels designed inthe form of extruded profile parts may only be produced up to a pistonsize of approximately 125 mm in diameter at the most without runninginto substantial problems. In the case of larger diameters it is nolonger possible to readily ensure the dimensional accuracy and thedesired low degree of roughness of the piston engaging bore defined bythe cylinder barrel to the desired degree. Consequently in the case ofdrive cylinders with a large piston diameter recourse is had toso-called tie rod cylinders in the case of which the cylinder barrel issmooth and circularly cylindrical and the cylinder heads are braced byrod-like ties distributed about the outer periphery of the cylinderbarrel. The type of design does however involve high costs of productionand requires technically complex features in order to provide foradditional functions of the above mentioned type or indeed of any type.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a drive cylinder moreparticularly in the form of a pneumatic cylinder, which even in the caseof large diameters renders possible an economic integration ofadditional functions with a high degree of manufacturing precision.

This object is to be achieved by a drive cylinder comprising a cylinderbarrel extending between two cylinder heads and a plurality of tiesdistributed about the outer periphery of the cylinder barrel and bracingthe cylinder heads, of which ties at least one is constituted by aprofile part which extends in the peripheral direction of the cylinderbarrel some distance along its outer periphery and whose profileprovides means for the implementation of at least one additionalfunction (referred to as “additional function means” in the following).

The drive cylinder unites the possibilities of accurate manufacture asin the case of conventional tie rod cylinders with the possibility ofeconomic integration of drive cylinders having a profiled cylinderbarrel so that it is possible to speak of a hybrid cylinder. Thecylinder barrel may have a geometry which is extremely simple toproduce, and more particularly it may have a preferably circularlycylindrical configuration, at least one tie however not being designedin the conventional manner as a tie rod but as a specially profiledcomponent (i.e. a profile part) which extends some distance along theouter periphery of the cylinder barrel and as regards its profile is sodesigned that additional function means are constituted, which permitthe implementation of at least one additional function. Such anadditional function may for instance be the attachment of sensors, ofcylinder accessories and/or of the cylinder itself or be the provisionof through channels for cables and/or hose and/or a drive fluid requiredfor the operation of the drive cylinder to run through.

Further advantageous developments of the invention are defined in thedependent claims.

In accordance with needs there is the possibility of designing onlyseveral or all the ties as profile parts of the type described. A designhas proved to be particularly advantageous in the case of which only twoties are present which are both in the form of profile parts, whichassume diametrally opposite positions in relation to the cylinderbarrel.

The peripheral extent of each profile part is conveniently so selectedthat the cylinder barrel is encircled along part of its periphery. Moreparticularly, each profile part may have such a peripheral extent thatit runs about at least 45° and preferably at least one 90° of the outerperiphery of the cylinder barrel, a particularly convenient range ofextent being between 90° and 180° of the peripheral extent of thecylinder barrel.

At the inner side facing the cylinder barrel at least one and preferablyall profile parts have an inner face adapted to the curvature of theoutline of the cylinder barrel, such adaptation being more particularlysuch that the radius of curvature of the inner face of the profile partis equal to or slightly larger than the radius of curvature of thecylinder barrel in the respective area.

In order not to impair an optimum relative position between the profileparts and the cylinder barrel during assembly and during operation, itmay be an advantage for the respective profile part to be arranged at acertain small radial distance from the outer face of the cylinderbarrel.

The drive cylinder may have particularly compact dimensions if at leastone and preferably each profile part is made with an arcuate curvaturein cross section, the concave part facing the cylinder barrel.

In order to ensure optimum bracing of the cylinder heads onto thecylinder barrel the length dimensions of the profile parts on the onehand and of the cylinder barrel on the one hand are preferably somatched that the profile part is arranged at an axial distance from thecylinder heads. The bracing action between the cylinder heads and thecylinder barrel is accordingly not obstructed by the profile parts.

It is particularly advantageous to have a design with at least one andpreferably all profile parts in the form of extruded parts of aluminummaterial. However a design in the form of a molding, more particularlyof plastic material, would also be possible.

In the following the invention will be explained with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first design of the drive cylinder of the invention in aperspective exploded view.

FIG. 2 represents a cross section taken through the drive cylinder ofFIG. 1 on the cross section line II-II in the part with the cylinderbarrel straddled by the profile parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drive cylinder generally referenced 1 is more particularly operatedwith compressed air as a drive fluid and accordingly finds applicationas a pneumatic cylinder. However, operation with a hydraulic actuatingfluid would also be possible.

The drive cylinder illustrated in FIG. 1 with shortened longitudinaldimensions possesses a spaced apart first and a second cylinder head 2 aand 2 b, between which a cylinder barrel 3 extends. The cylinder barrel3 possesses a relatively simple form with a smooth outer face and acylindrical configuration. Preferably, it is a question of a circularlycylindrical barrel 3.

As shown in FIG. 2 the cylinder barrel 3 preferably has the same wallthickness all around. In the case of the cylinder barrel 3 it ispreferably a question of a metal tube.

The two cylinder heads 2 a and 2 b are essentially plate-like in design,but however have an axial projection 4 on the inner side facing thecylinder barrel 3, the outline of the projection 4 being adapted to theinner form of the cylinder barrel 3 so that the latter is able to beplugged at the end face onto the respectively corresponding axialprojection 4. Accordingly there is an exact centering action between thecylinder heads 2 a and 2 b and the cylinder barrel 3 in the assembledstate thereof.

In the working embodiment on the radially facing peripheral face eachaxial projection 4 possesses a peripheral groove having a sealingrings—this only being illustrated in FIG. 1 in conjunction with thefirst cylinder head 2 a depicted on the left—and the sealing ringprovides a fluid-tight sealing action between the cylinder barrel 3 andthe respective cylinder head 2 a and 2 b.

The internal space 6 in the cylinder barrel 3 contains a piston, notillustrated in detail in the drawing, which by way of a seal arrangementis in hermetic contact with the inner face 7 of the cylinder head 3. Thepiston is able to move axially in relation to the cylinder barrel 3, themotion being transmitted to a power or force output member 8, which isaccessible outside the cylinder barrel 4. In the working embodiment thepower output member 8 is designed in the form of a piston rod, whichextends through the first cylinder head 2 a in a sealing manner to allowa sliding movement and in the inlet space 6 is kinematically coupledwith the piston, which is not illustrated. The section of the poweroutput member 8 placed outside the first cylinder head 2 a may beconnected. with any desired object to be moved.

The piston divides the internal station 6 into two axially followingworking spaces, in respect of which the supply and removal of theactuating fluid is possible. This takes place by way of a first and asecond fluid duct 12 a and 12 b, which respectively open at one end byway of one of the cylinder heads 2 a and 2 b into the respective workingspace and at the other end lead to a connection opening which is notillustrated in detail, same being located on the outer side, opposite tothe cylinder barrel 3, of the second cylinder head 2 b. Fluid lines maybe connected with the connection openings for the supply and removal ofthe actuating fluid.

By suitably controlled fluid actuation the piston may be the caused toperform an axial linear movement, which is available at the forcetransmitting member 8.

In order to ensure a firm axial connection together of the assemblycomprising the two cylinder heads 2 a and 2 b and the cylinder barrel 3the drive cylinder 1 is provided with a plurality of ties 13 arranged atthe outer periphery of the cylinder barrel 3, there being an arrangementof the ties 13 distributed in the peripheral direction 14, indicated bythe double arrow, of the cylinder barrel 3, the ties 13 extendingrespectively in axial parallelism to the cylinder barrel 3 between thetwo cylinder heads 2 a and 2 b. The ties 13 are respectively bracedaxially against cylinder heads 2 a and 2 b, something which is ensuredby means of bracing elements 15, which in the working example are in theform of bracing screws 15 a.

The dimensions, as measured athwart axis 16 of the drive cylinder 1, ofthe cylinder heads 2 a and 2 b are at least partially larger than theouter diameter of the cylinder barrel 3 so that the cylinder barrel 3 isradially overrun, the ties 13 being arranged between sections 17 a and17 b of the cylinder heads 2 a and 2 b, which in the fashion indicatedextend past the cylinder barrel 3. Accordingly the cylinder heads 2 aand 2 b have their sections 17 a and 17 b extending past the axiallyfacing end faces 18 a and 18 b of a respective tie 13.

At the sections 17 a and 17 b projecting past the cylinder barrel 3 eachcylinder head 2 a and 2 b is provided with a plurality of axial accessholes 22, through which bracing screws 15 a extend, the screw heads 23bearing against the associated cylinder head 2 a and 2 b. The shanks 24of the screws are screwed into aligned attachment holes 25 for theassociated tie 13, such holes being open toward the respective end face18 a and 18 b. The female threads in the attachment holes 25 arepreferably tapped by the threaded shanks 24 on screwing in.

In the working embodiment the longitudinal dimensions of the ties are somatched to the length of the cylinder barrel 3 that when the cylinderheads 2 a and 2 b are firmly braced against end faces of the cylinderbarrel 3 there is a small axial clearance between the ties 13 and atleast one of the cylinder heads 2 a and 2 b. Accordingly it is possibleto ensure that by bracing or tightening the ties 13 and the cylinderheads 2 a and 2 b the latter are firmly braced against the end faces ofthe cylinder barrel 3 and accordingly the cylinder barrel 3 is firmlyclamped between the cylinder heads 2 a and 2 b.

Since the cylinder barrel 3 is seated on the axial projections 4 with acentering action, an alternative design would be possible where in theclamped or braced state the ties 13 would have their end faces 18 a and18 b firmly thrust against the cylinder heads 2 a and 2 b and thecylinder barrel 3 would be held with a small degree of axial playbetween the cylinder heads 2 a and 2 b.

A particular feature of the ties 13 is that they are respectivelyconstituted by a profile part 26, which extends some distance in theperipheral direction 14 of the cylinder barrel 3 along the outerperiphery of this cylinder barrel 3, the selected type, owing to theselected type of profile, simultaneously forming the additional functionmeans 27 being designed to perform at least one additional function.These integrated additional function means 27 render it possible for theties 13 to be employed for other purposes besides their tie function.

The design of the ties 13 in the form of profile parts 26 in thiscontext provides the advantage of a substantial degree of freedom asregards the design of the additional function means. This is moreparticularly the case when the profile parts 26, as in the workingexample, are in the form of extrudes of more especially aluminummaterial. By suitably designing the extrusion die profile parts may beproduced which are highly adaptable as regards the respectiveapplication.

The design in the form of extrudes is as a rule to be preferred to adesign, also possible in principle, as moldings, although in the case ofplastic parts may be produced which lead to a considerable economy inweight.

The number of the profile parts 26 present and undertaking a tiefunction is in principle unrestricted, although it is convenient to haveat least two such profile parts 26, as in the case in the workingembodiment. An alternative structure, in the case of which the ties 13are only partly in the form of profile parts and partly are in the formof rod-like ties, is not illustrated in the drawing in detail.

More particularly for reasons of symmetry the two profile parts 26 ofthe working embodiment are placed at diametrally opposite positions onthe cylinder barrel 3 and respectively a peripheral extent in thedirection 14 is selected which means that the cylinder barrel 3 isencircled respectively for part of its periphery by the respectiveprofile part 26. The peripheral extent of the profile parts 26 is in theworking example respectively in a range of 90° to 180° of the peripheralextent of the cylinder barrel 3. It is an advantage for the peripheralextent of a respective profile part 26 to be at least so large that itextends for at least 45° and preferably for at least 90° of the outerperiphery of the cylinder barrel 3. Extremely compact dimensions of thedrive cylinder 1 may be realized if the profile parts 13 are curved inan arcuate manner as seen in cross section, the concave portion beingturned toward the cylinder barrel 3. Accordingly a configuration of theprofile part 26 is possible in the case of which same directly followsthe course of the periphery of the cylinder barrel 3.

This is further aided in the working example because the profile parts26 have an inner face 28, at the concave inner side facing the cylinderbarrel, with a curvature corresponding to the outline of the cylinderbarrel 3. The radius of curvature of these inner faces is in the workingexample the same as that of the facing outer face 32 of the cylinderbarrel 3, but may also be slightly larger than it, more particularlywhen the respectively profile part 26 is at a small radial distance fromthe outer face 32 of the cylinder barrel 3.

It will furthermore appear from FIG. 2 that when there are severalprofile part 26 the profile parts which are adjacent to each other inthe peripheral, may be placed at a distance apart from each other. Thefacing section of the outer face 32, covered by the profile parts 26, ofthe cylinder barrel 3 may be limited to those areas, in which anadditional function is to be made available.

As shown in FIG. 2 the profile parts 26 preferably generally are madethicker than the wall of the cylinder barrel 3. This renders it moreparticularly possible to achieve an integration of the additionalfunction means 27 in the interior of a respective profile part 26.

In the working embodiment additional function means 27 are accordinglyprovided, which constitute a peripherally closed channel 33, whichextends through one of the profile parts 26 in the longitudinaldirection and opens at both end faces 18 a and 18 b. This channel 13 isa component of the first fluid duct 12 a, through which the drive fluidmay be pumped from the rear second cylinder head 2 b to the front firstcylinder head 2 a.

A similar channel 33′ is also present in the profile part 26, whichhowever in the working embodiment is not utilized for fluid transfer.

As furthermore shown in FIG. 2 such parts of the material of the profileparts 26, which are not required for additional functions, may have oneor more cavities 34 extending in the longitudinal direction, which forexample economize in the use of material.

In other respects the cavities 34 may also be employed as channel-likeadditional function means and for example serve to accommodateelectrical cables and/or hose, which are to be laid in the longitudinaldirection of the cylinder barrel 3 and for example are employed inconjunction with sensor means.

In the working embodiment the profile parts 26 furthermore possessadditional function means 27, which constitute attachment means 35.These attachment means 35 may more especially be designed in the form ofattachment grooves or slots, which may be employed for the attachment ofsensors and/or cylinder accessories and/or the drive itself.

For reasons of simplification of production of the profile parts 26 thedesired attachment means 35 may be provided as required, different typesof attachment means 35 being able to be realized simultaneously to beavailable for later use.

1. A drive cylinder comprising: a cylinder barrel extending between two cylinder heads and a plurality of ties distributed about the outer periphery of the cylinder barrel and bracing the two cylinder heads, the plurality of ties are each constituted by a profile part which extends a distance in a peripheral direction of the cylinder barrel; the plurality of profile parts are spaced from each other in the peripheral direction of the cylinder barrel, at least one of the plurality of profile parts on an inner side facing the cylinder barrel includes an inner face, and the inner face is adapted to the curvature of the outline of the cylinder barrel: and at least on of the plurality of profile parts provides means for implementation of at least one additional function.
 2. The drive cylinder as set forth in claim 1, wherein two profile parts are diametrally oppositely arranged.
 3. The drive cylinder as set forth in claim 1, characterized in that the peripheral extent of at least one of the plurality of profile parts is so selected that it embraces the cylinder barrel along a part of its outline.
 4. The drive cylinder as set forth in claim 1, characterized in that the radius of curvature of the inner face of at least one of the plurality of profile parts is equal to or slightly larger than the radius of curvature of the cylinder barrel adjacent to the at least one profile part.
 5. The drive cylinder as set forth in claim 1, characterized in that at least one of the plurality of profile parts is curved in an arcuate manner as seen in cross section, the concave side thereof being turned toward the cylinder barrel.
 6. The drive cylinder as set forth in claim 1, characterized in that the longitudinal dimension of at least one of the plurality of profile parts on the one hand and of the cylinder barrel on the other hand are so matched to each other that between the at least one profile part and at least one of the two cylinder heads there is an axial clearance.
 7. The drive cylinder as set forth in claim 1, characterized in that at least one of the plurality of profile parts is constituted by an extrude.
 8. The drive cylinder as set forth in claim 1, characterized in that at least one of the plurality of profile parts is constitute by a molding.
 9. The drive cylinder as set forth in claim 1, characterized in that at least one of the plurality of profile parts is manufactured of aluminum material or of plastic material.
 10. The drive cylinder as set forth in claim 1, characterized in that at least one of the plurality of profile parts has such a peripheral extent that extends for at least 45° of the periphery extent of the cylinder barrel.
 11. The drive cylinder as set forth in claim 10, characterized in that the peripheral extent of the at least one profile part is in a range of 90° to 180° of the peripheral extent of the cylinder barrel.
 12. The drive cylinder as set forth in claim 1, characterized in that at least one of the plurality of profile parts extends over one or more cavities extending along the full length.
 13. The drive cylinder as set forth in claim 1, characterized in that the additional function means constitute attachment means, which are provided in the form of one or more attachment grooves and which are provided for the attachment of sensors and/or the drive cylinder itself.
 14. The drive cylinder as set forth in claim 1, characterized in that the additional function means constitute peripherally closed channels for fluid and/or cables and/or hose to run in.
 15. The drive cylinder as set forth in claim 1, characterized in that the cylinder barrel is cylindrical.
 16. The drive cylinder as set forth in claim 1, characterized by attachment holes open toward the end faces of the at least one of the plurality of profile parts, into which holes attachment screws acting on the associated cylinder heads are screwed.
 17. A drive cylinder comprising: a cylinder barrel extending between two cylinder heads and a plurality of ties distributed about the outer periphery of the cylinder barrel and bracing the two cylinder heads, at least one of the plurality of ties is constituted by a profile part which extends a distance in the peripheral direction of the cylinder barrel, the profile part provides means for implementation of at least one additional function, and a longitudinal dimension of the at least one profile part and a longitudinal dimension of the cylinder barrel are so matched to each other that between the profile part and at least one of the two cylinder heads there is an axial clearance.
 18. A drive cylinder comprising: a cylinder barrel extending between two cylinder heads and a plurality of ties distributed about the outer periphery of the cylinder barrel and bracing the cylinder heads, at least one of the plurality of ties is constituted by a profile part which extends a distance in the peripheral direction of the cylinder barrel, the profile part provides means for implementation of at least one additional function, and the additional function means constitute peripherally closed channels for fluid and/or cables and/or hose to run in.
 19. A drive cylinder comprising: two cylinder heads; a cylinder barrel extending between the two cylinder heads; and at least two profile parts distributed about an outer periphery of the cylinder barrel and bracing the two cylinder heads, the at least two profile parts extend a distance in a peripheral direction of the cylinder barrel and the at least two profile parts are spaced from each other in the peripheral direction of the cylinder barrel, at least one of the at least two profile parts on an inner side facing the cylinder barrel includes an inner face, and the inner face being adapted to the curvature of the outline of the cylinder barrel. 